Ink ribbon lubrication by liquid silicone oil

Abstract

High speed printing machine incorporating a pressure-sensitive transfer ribbon of the squeeze-out or reusable type having a thin, flexible plastic film foundation having bonded thereto a microporous resinous ink layer containing pressure-exudable liquid ink which is adapted to be pressure-transferred to a copy sheet by means of a printing element which makes momentary impression contact with the ribbon while the ribbon is moving slowly across the path of said printing element. The invention comprises a high speed printing or impact machine which includes means for the application of a thin friction-reducing or slip-permitting film of liquid silicone oil to the rear or impact surface of the transfer ribbon in order to reduce the friction between the printing element and the moving transfer ribbon and to prevent grabbing of the film foundation and breakdown of the bond between the film foundation and the ink layer.

I claim: 
     
       1. High speed printing apparatus adapted to feed a copy sheet and a pressure-sensitive transfer ribbon, comprising a flexible plastic film foundation supporting an ink-releasing layer on the front surface thereof, through a print station and to apply imaging pressure against the rear surface of said ribbon to cause imagewise transfer of ink from said layer to the surface of said copy sheet, said apparatus comprising a print station including an imaging element and a backing element spaced therefrom, means for forcing said elements together to impart an imaging pressure therebetween, means for feeding a said copy sheet through said print station so that the ink-releasing layer thereof is adjacent said copy sheet and the rear surface thereof is adjacent said imaging element, characterized by the presence of means for applying a thin, substantially continuous liquid film of silicone oil to the said rear surface of the pressure-sensitive transfer ribbon at a location in advance of the movement of said ribbon into said print station so that said ribbon carries said film of silicone oil at the time that the rear surface thereof is engaged by said imaging element. 
     
     
       2. An apparatus according to claim 1 in which said ribbon feeding means is adapted to impart substantially continuous feeding movement to said ribbon. 
     
     
       3. An apparatus according to claim 1 which includes means for moving said backing element against said imaging element to impart said imaging pressure. 
     
     
       4. An apparatus according to claim 1 in which said silicone oil-applying means comprises a coating roller, the surface of which is adapted to be provided with a continuous film of silicone oil and which is engaged by the rear surface of said transfer ribbon. 
     
     
       5. An apparatus according to claim 4 in which said coating roller has a gravured surface. 
     
     
       6. An apparatus according to claim 1 which further comprises means for supplying a length of said transfer ribbon to said oil-applying means and to said print station and means for collecting said transfer ribbon after it exits said print station. 
     
     
       7. In the method of forming a copy on a high speed printing machine in which a copy sheet and a pressure-sensitive transfer ribbon comprising a flexible polyethylene terephthalate polyester plastic film foundation supporting an ink-releasing layer on the front surface thereof are superposed and continuously fed through a printing station where a rapid succession of imaging pressures are applied against the rear surface of said transfer ribbon by means of an imaging element to effect the transfer of ink from said ink-releasing layer to said copy sheet to form a succession of images there, the improvement of which comprises coating the rear surface of said film foundation with a substantially-continuous thin film of liquid silicone oil to facilitate the disengagement of said imaging element from said transfer ribbon.